Sponsor Area

Environmental Issues

Question
CBSEENBI12002564

Which two of the following changes (1-4) usually tend to occur in the plain dwellers when they move to high altitudes (3500 m or more)?

1) Increase in red blood cell size
2) Increase in red blood cell production
3) Increase in breathing rate
4) Increase in thrombocytes count

Changes occurring are

  • (2) and (3)

  • (3) and (4)

  • (1) and (4)

  • (1) and (2)

Solution

A.

(2) and (3)

When a person moves to higher altitudes, the PO2 and total atmospheric pressure decrease. Hypoxia stimulates the JG - cells of the kidney to release erythropoietin hormone, which stimulates erythropoiesis in bone marrow causing polycythemia. Hypoxia will also increase breathing rate. Initially, the size of RBCs will also increase but with an increase in number of RBCs, the size of RBCs becomes normal.